VTOL Testing

How-to test that the VTOL functions properly, main focus are transitions:

On the bench

In flight

General notes on transitions

There are currently 3 ways of commanding the VTOL to transition:

RC switch (2 pos, aux1)

MAVLink command (MAV_CMD_DO_VTOL_TRANSITION)

Transition during mission (MAV_CMD_DO_VTOL_TRANSITION internally)

When a transition is commanded (by either of the methods above), the VTOL enters the transition phase. If the VTOL receives a new transition command back to the old state during an ongoing transition it will switch back instantly. This is a safety feature to abort the transition when necessary. After the transition has been completed, the VTOL will be in the new state and a commanded transition into the reverse direction will take place normally.

Make sure the AUX1 channel is assigned to an RC switch and that airspeed is working properly.

On the bench

Remove all props! To test transition functionality properly, the vehicle needs to be armed.

By default, starting in multirotor mode:

arm the vehicle

check that motors are running in multirotor configuration (rudders/elevons should not move on roll/pitch/yaw inputs)

toggle transition switch

(if applicable) wait on step 1 of the transition phase to complete

blow into pito tube to simulate airspeed

(if applicable) step 2 of the transition phase will be executed

check that motors are running in fixed-wing configuration (roll/pitch/yaw inputs should control rudders/elevons)

toggle transition switch

observe back transition

check that motors are running in multirotor configuration (rudders/elevons should not move on roll/pitch/yaw inputs)

In flight

Before testing transitions in flight, make sure the VTOL flies stable in multirotor mode. In general, if something doesn't go as planned, transition to multirotor mode and let it recover (it does a good job when it's properly tuned).

In-flight transition requires at least the following parameters to match your airframe and piloting skills:

it looses control while gaining speed (this can happen due to many factors)

the transition takes too long and it flies too far away before the transition finishes

For 1): Switch back to multirotor (will happen instantly). Try to identify the problem (check setpoints).

For 2): If blending airspeed is set and it has a higher airspeed already it is controllable as fixed-wing. Therefore it is possible to fly around and give it more time to finish the transition. Otherwise switch back to multirotor and try to identify the problem (check airspeed).

FW-MC

The transition from FW to MC is mostly unproblematic. In-case it seems to loose control the best approach is to let it recover.

Automatic transition test (mission, commanded)

Commanded transitions only work in auto (mission) or offboard flight-mode. Make sure you are confident to operate the auto/offboard and transition switch in flight.

Switching to manual will reactivate the transition switch. For example: if you switch out of auto/offboard when in automatic fixed-wing flight and the transition switch is currently in multirotor position it will transition to multirotor right away.

Proceduce

The following procedure can be used to test a mission with transition:

upload mission

takeoff in multirotor mode and climb to mission height

enable mission with switch

observe transition to fixed-wing flight

enjoy flight

observe transition back to multirotor mode

disable mission

land manually

During flight, the manual transition switch stays in multirotor position. If something doesn't go as planned, switch to manual and it will recover in multirotor mode.

Example mission

The mission should contain at least (also see screenshots below):

(1) position waypoint near takeoff location

(2) position waypoint in the direction of the planned fixed-wing flight route

(3) transition waypoint (to plane mode)

(4) position waypoint further away (at least as far away as the transition needs)

(6) position waypoint to fly back (a bit before takeoff location so back transition takes some distance)